In my experience, most American Jews support the concept of Israel, and would most definitely state that they want stability and peace for Israel, but they also very much identify with being ‘thoughtful’ and social justice oriented, and so find it difficult when it comes to the Palestinian issue. Plus, I think for some the necessary militarization of Israel is problematic. It's actually a discussion that should be had out in the open, IMHO.
The rise of anti-semitism in Europe is very disturbing. To me, all of it is bizarre. For instance, how can the left be so adoring about the sociopolitical philosophy of Marx, an ancestral Jew, but be at the same time anti-semitic? Conversely, how can so many Jews be left-leaning when so much anti-semitism comes from the left?
All of it sickens me. Incidentally, again IMHO, no group uses identity politics as much and as divisively as the left - and you are seeing it in this campaign as the race card, the gender card, the formal education level card, and the class warfare card are all being pulled out - as usual. It's important to remember that identity politics was at the root of some of the most tragic events (e.g. genocide) in human history, and using it like the left does is extremely irresponsible - at best.
My Jewish lady friend suggested it comes from interbreeding. Not many left after the Holacost.